Wheel axle suspension

ABSTRACT

A wheel axle suspension for suspending a round hollow axle ( 10 ) from a vehicle comprises on both sides of the vehicle a trailing arm ( 1,41,51 ) to which the axle ( 10 ) is attached. The trailing arm is hingedly connected at the front to a bearing bracket ( 42 ) which is arranged on the vehicle chassis ( 43 ). A pneumatic spring ( 44 ) is operational between the trailing arm and the chassis. The axle body bears directly against a contact region ( 5,45,55 ) of the trailing arm. The contact region is essentially complementary to the outer contour of the axle body, wherein, on that side of the axle body opposite the contact region, a support part ( 20,46,56 ) is provided with a recess ( 21 ) for accommodating the axle. The support part is clamped against the axle by means of clamping means ( 23,24,47,48 ). At the location of the contact region, the trailing arm is wider than in the region ( 2,41   a,    52 ) which is situated immediately in front thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/NL2008/000177, filed Jul. 18, 2008, which claims the benefit ofNetherlands Application Nos. 1034171, filed Jul. 20, 2007 and 1034756,filed Nov. 23, 2007, the contents of all of which are incorporated byreference herein.

FIELD OF THE INVENTION

The invention relates to the field of a wheel axle suspension forsuspending an axle body of a wheel axle from a vehicle, in particular aroad vehicle, such as a lorry or a lorry trailer.

In particular, the invention relates to the field in which a wheel axlesuspension, on each side of the vehicle, has a suspension arm whichextends substantially in the longitudinal direction of the vehicle,called a “trailing arm” in the art, and to which the axle body isattached, each trailing arm being hingedly connected at the front,viewed in the direction of travel of the vehicle, to a bearing bracketwhich is arranged on the vehicle chassis. In a known embodiment, apneumatic spring is arranged between the trailing arm and the chassis ofsuch a wheel axle suspension.

Trailing arms for wheel axle suspensions of this kind can essentially bedivided into two types: spring trailing arms (also referred to asflexible trailing arms) and rigid trailing arms. In practice, aresilient bush is used for connecting rigid trailing arms to a bearingbracket which is mounted on the vehicle chassis, in which case theresilient bush absorbs relative movements of the wheel axle suspension.In the case of wheel axle suspensions which use spring trailing arms,the majority of the relative movements are absorbed by the deformationof a spring portion of the trailing arm itself. In this case, the springtrailing arm is often produced in the form of a monolithic and solidpart from a suitable steel grade, in particular spring steel. The springportion is situated between the area where the wheel axle is connectedto the trailing arm and the front end of the trailing arm, where the armis hingedly attached to a bearing bracket. The different operationalprinciples of the trailing arms result in different requirements imposedon the trailing arms. Spring trailing arms are designed to be able tocope with relatively large deformations without breaking Thisrequirement also has consequences for the production of the trailingarms.

The invention relates inter alia to the trailing arm of a wheel axlesuspension of this type, both with regard to the design of the trailingarm and with regard to the method for the production of a trailing armof this type.

The invention also relates to the production of wheel axle suspensionsof this type, in particular the production of such wheel axlesuspensions for wheel axles having different diameters.

A first aspect of the invention relates to the contact of the axle bodyand the trailing arm in the case of a wheel axle suspension.

A wheel axle suspension is disclosed in, for example, DE 296 15 286.With this known wheel axle suspension, the axle body is clamped directlyagainst a contact region of a spring trailing arm by means of a clampingplate which is situated on that side of the axle body which is turnedaway from the trailing arm, and by a pair of U-shaped clamping strapsextending around the trailing arm and through holes in the clampingplate. At the location of the axle clamp, the axle body is deformed toform a non-round contour with flattened regions which contact thecontact region of the trailing arm. Here, the spring trailing arm has aconstant width, that is to say, the contact region and the springportion have the same width.

BACKGROUND OF THE INVENTION

In order to save material, weight and space in the structure, thebearing springs are generally designed to be as narrow as possible, withthe trailing arm still having a width and height which are such that therolling motions of the vehicle can still be absorbed to a sufficientdegree. In the case of the spring trailing arm from DE 296 15 286, thisresults in the axle body which extends at right angles to the trailingarm being only clamped in over a limited length of the axle body. As aresult thereof, the axle body is subjected to high loads locally, due tothe high clamping forces which are required to fix the axle.Particularly with thin-walled tubular axle bodies, this is a problem asthese axle bodies, due to the great forces, are deformed significantlywhich adversely affects their service life. It is known to increase thelength of the axle body which is clamped in by using an axle pad whichis arranged between the trailing arm and the axle body and is wider thanthe trailing arm. Such a structure is shown, for example, in FIG. 7 ofDE 296 15 286, but has the drawback that more parts are required whichresults in a more complicated fitting.

It should be noted that US 2006/0163834 discloses a wheel axlesuspension having a rigid trailing arm which is produced by casting orforging and is provided with a sleeve through which the axle bodyextends in the fitted state. The sleeve may be formed as a single part,with the axle body having to be pushed into the latter in the axialdirection, but the sleeve may also be made up of two halves which arewelded to one another by means of axial welding after the axle body hasbeen placed therein. The sleeve is wider than that part of the trailingarm which is situated in front thereof. The sleeve is designed to bewelded to the axle body. To this end, the sleeve has openings in which aplug weld or the like can be provided for connecting the sleeve to theaxle body.

SUMMARY OF THE INVENTION

It is an object of the first aspect of the invention to provide animproved wheel axle suspension.

This object is achieved, according to the first aspect of the invention,by means of a wheel axle suspension according to the present invention.The trailing arm is wider at the location of at least the front of thecontact region than in the region which is situated immediately in frontthereof.

In one embodiment as a spring trailing arm, the trailing arm at thelocation of at least the front end of the contact region is wider thanthe spring portion of the trailing arm, which is situated more to thefront. In practice, the spring trailing arm is usually provided with anintegrally formed securing eye and the spring portion is situatedbetween that securing eye and the contact region, the trailing armhaving a significantly greater stiffness at the location of the contactregion than the spring portion.

The first aspect of the invention makes it possible to make the designthe trailing arm lightweight, while still clamping a sufficient lengthof the axle body to spread the load on the axle body resulting from theclamping and thus preventing the axle body from being subjected tolocally excessive loads and to deformation, while not requiring anyadditional components between the axle body and the trailing arm.

It has been found that the axle body is mainly loaded and deformed atthe front of the clamping arrangement. This makes it possible to taperthe portion of the trailing arm which forms the contact region towardsthe rear, i.e. to reduce the width thereof towards the rear. At thefront of the clamping arrangement, the axle body is then clamped over asufficient length of the axle body, while the axle body is clamped overa smaller length at the rear of the clamp. This results in a saving inmaterial and weight.

For example, the portion of the trailing arm which forms the contactregion for the axle body, in top view, has an approximately triangularshape, the greatest width of which is situated at the front of saidportion and the tip of the triangle being situated at the rear of thatportion. This embodiment can be used in particular when the support partis provided with a securing arm for the pneumatic spring, preferablyintegrally formed with the support part, wherein the axle body isclamped between the trailing arm and the support part, and wherein thesecuring arm extends further towards the rear. In that case, forexample, clamping means are provided which clamp the trailing arm andthe support part against the axle body. For example, two holes are thenprovided near the wide front of that portion of the trailing arm whichforms the contact region, and a single hole is provided at the narrowerrear of said portion, for example in order to accommodate three clampingbolts (or one U-shaped strap and one bolt).

Preferably, the axle body has a substantially circular cross section atthe location of the axle clamping arrangement. Axle bodies having acircular cross section are more capable of absorbing moments of torsionthan axles with a different cross section, for example a square crosssection. In addition, it is preferable to use a hollow axle body.

In a preferred embodiment, the support part surrounds the preferablyround and hollow axle body over at least 180° of its periphery. As aresult, the clamping force is distributed evenly over the periphery ofthe axle body and the axle body is prevented from becoming excessivelydeformed and deviating from a circular shape to an excessive degree. Asa result of this measure, relatively thin-walled axle bodies can be usedwhich in itself results in a weight saving of the vehicle.

In one possible embodiment, the support part is omitted and the trailingarm, at the location of the axle clamping arrangement is provided withholes on both sides of the axle, for inserting the shanks of U-shapedclamping straps. As a result of this measure, it may be possible toachieve a weight saving.

Preferably, the trailing arm is designed as a spring or flexibletrailing arm. The rolling motions about the longitudinal axis of thevehicle are absorbed by these spring trailing arms.

In another possible embodiment, the trailing arm is designed as a rigidarm. Such rigid arms are hingedly connected to the bearing bracket bymeans of a resilient bush.

Preferably, the trailing arm and the axle body are locked with respectto one another by means of a locking means. As a result of this lockingaction, a rotation of the axle body with respect to the trailing arm dueto torsional forces is prevented. Preferably, the axle body or trailingarm is provided with a projection at the location of the axle clampingarrangement and the trailing arm or axle body, is provided with acomplementary recess for accommodating the projection.

If a support part is used, the support part may be provided withrecesses for accommodating at least a bend portion of U-shaped clampingstraps.

It is an object of a second aspect of the invention to improve, in apneumatically sprung wheel axle suspension, the attachment of the axlebody to the trailing arm by means of the clamping means and/or toprovide an alternative solution.

The second aspect of the invention provides a pneumatically sprung wheelaxle suspension according to. In this case, the portion of the trailingarm which forms the contact region for the axle body has two holes atthe front of the contact region and one hole at the rear of the contactregion, with the clamping means extending through these holes. Thissolution is based on the insight that the load on the axle body and anydeformation of the axle body primarily takes place at the front of theclamping arrangement. In this case, the axle body is preferably hollowand advantageously has a circular cross section.

The solution according to the second aspect of the invention makes itpossible to design the wheel axle suspension with fewer and/or smallerclamping means compared to the prior art, which facilitates mounting andcan result in a saving on material and weight.

Preferably, the trailing arm is a spring trailing arm. In this case, theportion between the part where the trailing arm is hingedly connected tothe bearing bracket and the contact region is the spring portion.

Preferably, the trailing arm is wider at the front of the contact regionthan at the rear of the contact region. As a result thereof, it ispossible to achieve a saving on material and thus weight as well.

In one possible embodiment, the contact region has a substantiallytriangular shape when viewed from the top, in particular a shape whichis substantially similar to that of an equilateral triangle.

In one possible embodiment, the clamping means are three bolts, the boltshanks of which extend through the holes, with the bolt shank at therear of the contact region having a larger cross section than the boltshanks at the front of the contact region. As a result thereof, thecross section of the clamping means can be adapted to the load, forexample in such a manner that the stresses in the clamping means areequal on both sides of the contact region.

In order to save material and thus weight without significantly reducingthe strength of the trailing arm, it is possible to provide a depressionwhich extends from one of the two holes at the front of the portionwhich forms the contact region in the direction of the hole at the rearof said portion.

In an advantageous embodiment, that portion of the trailing arm whichforms the axle clamping arrangement has a central rib on the side whichis turned away from the axle body which extends from the front of theportion which forms the contact region, between the two holes at saidfront, in the direction towards the single hole at the rear, adepression being provided on either side of this central rib wherein, ineach case, one of the holes at the front is situated, with a further ribpreferably being present along each side edge of the respective portionwhich delimits the depression on that side.

Preferably, the trailing arm is at least partially produced by forging.Preferably, at least the portion which forms the contact region isproduced by forging. As will be explained below, the entire trailing armis preferably produced by forging, with a securing eye at the front ofthe trailing arm being brought into the intended position after forgingby twisting the trailing arm, if desired.

A third aspect of the invention relates to a wheel axle suspension,wherein an absorber is also provided, in practice usually a shockabsorber having a telescopic body provided with mounting eyes on theends of the body.

It is an object of the third aspect of the invention to provideimprovements and/or to present alternatives for the attachment of suchan absorber to that side of the absorber turned towards the trailingarm.

In a first variant according to the third aspect of the invention, aseparate absorber securing part is provided which is provided with oneor more lips or a fork for hingedly attaching an eye of a shockabsorber, which absorber securing part is clamped between the trailingarm and the support part in the fitted position.

Preferably, the absorber securing part has a rear concave surface which,in the fitted position, contacts the axle body.

Preferably, the absorber securing part has one or more through-holesthrough which in each case one leg of a clamping means extends.

In a second variant according to the third aspect of the invention, aseparate absorber securing part with a bush is provided through which,in the fitted position, a shank of one of the clamping means, forexample a clamping bolt or clamping strap, extends, by means of whichclamping means the bush is clamped against the trailing arm or supportpart, the bush being provided with one or more lips or a fork forhingedly attaching an eye of a shock absorber.

In a third variant according to the third aspect of the invention, it isprovided that the absorber attachment is integrally formed with one ofthe clamping means, for example one clamping means is designed as a boltwith a bolt shank and a bolt head, the bolt head being provided with oneor more lips or a fork for hingedly attaching an eye of a shockabsorber.

A fourth aspect of the invention relates to the attachment of a possibleabsorber to the chassis. In practice, a shock absorber is usuallyprovided between the trailing arm and the chassis, with the absorberusually having a telescopic body having an eye at each end of the bodyfor attaching the absorber to the trailing arm and the chassis.

According to the fourth aspect of the invention, a structure having,among other things, a separate absorber securing part which is providedwith one or more lips or a fork for hingedly attaching an eye of a shockabsorber, which absorber securing part, in a fitted position, isdirectly connected to the vehicle chassis. This has the advantage thatthe forces are passed on directly to the vehicle chassis by the shockabsorber and do not pass via the bearing bracket. As a result thereof,the bearing bracket can be optimized further for hingedly supporting thetrailing arm. Furthermore, the fitting of the bearing bracket can besimplified if the shock absorber is no longer connected to the bearingbracket.

In one preferred embodiment, the absorber securing part is provided withan integral bolt shank, preferably a single integral bolt shank, whichis inserted through an opening in the chassis of the vehicle and securedby means of a nut. This measure simplifies the fitting. In this case,the absorber securing part can be used to replace the normal bolt/nutconnection, as a result of which the number of bolt/nut connectionsremains the same.

A fifth aspect of the invention relates to the efficient production ofpneumatically sprung wheel axle suspensions, in particular wheel axlesuspensions for wheel axles with different cross-sectional dimensions.

In practice, hollow tubular wheel axles having a circular cross sectionand an outer diameter of 127 mm are often used for lorries. Fortrailers, hollow tubular wheel axles having a circular cross section andan outer diameter of 146 mm are often used. Other diameters are alsoknown.

It is an object of the fifth aspect of the invention to make efficientproduction of pneumatically sprung wheel axle suspensions possible.

To this end, the fifth aspect of the invention provides an assembly fora wheel axle suspension for suspending an axle from a vehicle. Accordingto this aspect, the assembly comprises a shell part which can be fittedbetween the contact region of the trailing arm and the axle body, whichshell part has an outer contact surface which is designed to bear in afitting manner against the contact region which has a diameter which isadapted to the first diameter and has an inner contact surface which isdesigned to bear against an axle body having a second diameter, thesecond diameter being smaller than the first diameter.

According to the fifth aspect of the invention, it is provided that thetrailing arm is produced for an axle body having a large outer diameter,for example 146 mm, but that it can also be used for axle bodies havinga smaller diameter, for example 127 mm.

Preferably, with this aspect of the invention, the support part isprovided with a recess which is adapted to the outer diameter of theaxle body. In this manner, a universal trailing arm for axle bodies ofdifferent diameters can be produced, while a specific support part and,if desired, a specific shell part are produced for each variantembodiment.

The fifth aspect of the invention also relates to a method for producingwheel axle suspensions for wheel axles having axle bodies of differentdiameters, wherein use is made of the abovementioned assembly, wherein,based on the diameter of the axle body, no shell part or a shell partadapted to the diameter is fitted between the axle body and the trailingarm. In one preferred embodiment, different support parts having arecess adapted to the different diameters of the axle bodies arefurthermore provided, with a support part being selected and fitted inthe wheel axle suspension based on the diameter of the respective axlebody.

A sixth aspect of the invention relates to the production of a springtrailing arm for a pneumatically sprung wheel axle suspension.

As has already been mentioned, the trailing arms for such a wheel axlesuspension can be divided into two types: sprung and rigid trailingarms. Rigid trailing arms are connected to a bearing bracket on avehicle chassis by means of a resilient bush, with the resilient bushabsorbing the relative movements of the wheel axle suspension. Withwheel axle suspensions which use spring arms, the majority of therelative movements are absorbed by the deformation of a spring portionof the trailing arm itself. This spring portion is situated between thearea where the axle is connected to the trailing arm and the front endof the arm, where the arm is hingedly suspended from a bearing bracket.The various operational principles result in different requirementsbeing imposed on the trailing arms. Spring trailing arms are designed tobe able to cope with relatively large deformations without breaking Thisrequirement also has consequences for the production of the trailingarms.

It is known to produce rigid structures which do not allow greatdeformations by means of casting or forging. An example thereof is therigid trailing arm from US 2006/0163834. This trailing arm is of therigid type and is therefore only suitable for wheel axle suspensionswherein the resilient bush absorbs the deformations. A drawback of thesewheel axle suspensions is the fact that these are less suitable forabsorbing rolling motions of the vehicle.

By tradition, spring trailing arms have a substantially rectangularcross section and, according to the prior art, are always produced byrolling. By deforming and kneading the material during the rollingprocess, the trailing arm becomes resilient, thus preventing thetrailing arm from breaking in the event of relatively smalldeformations. However, rolling has the drawback that passing a(semi-finished) product between two rollers results in the cross sectionof the product being unambiguously determined in one direction and novariation in cross section is possible, in principle, viewed in thelongitudinal direction of the trailing arm.

Some variation in the cross section is still possible if the(semi-finished) product is not passed between the two rollers in itsentirety, but is pulled back in time. Another option would be to movethe rollers towards one another or further apart while the product isbeing passed through. Apart from the fact that this requires acomplicated control unit for the process, the shape of the trailing armis largely limited due to the production process.

Some variation in cross section also occurs because the rolling processusually only determines the thickness with sufficient accuracy. Thedimensions in the other two directions, i.e. the longitudinal directionand the width direction, cannot be controlled in principle. All this isdependent on the starting material. Different starting materials lead todifferent end products, so that there is insufficient control over thethree-dimensional dimensions of the product.

It is an object of the sixth aspect of the invention to provide animproved and/or alternative manufacturing method for the spring trailingarm.

According to the sixth aspect of the invention, the spring trailing armis at least partially produced by forging. This has the advantage thatthe shape of the trailing arm is not limited to such a large degree bythe manufacturing process. This offers more freedom in terms of designand can lead to savings on material, weight and space.

If there is more freedom in terms of design this offers the possibilityof optimizing the design of a spring trailing arm further. Optimizationof the trailing arm is desirable if, for example, the trailing arm isnot only subjected to flexural loads, but, for example, also totorsional loads as a result of, inter alia, the rolling motion of thevehicle. By now using forging during the manufacturing process, moreshapes are possible for the trailing arm.

A greater degree of freedom of design offers the advantage that parts ofthe trailing arm can be optimized for the function they perform. As aresult, the trailing arm can be made more lightweight and still besufficiently strong locally to absorb the loads to which it issubjected. Ultimately, the freedom of design leads to savings inmaterial, weight and/or space.

Preferably, the trailing arm is made of spring steel.

Preferably, the trailing arm is made in its entirety in a singleoperation from the starting material. In other words, the trailing armis preferably formed by one blow of the forging device.

With the invention, it is possible to carry out the forging on a rolledand/or cast semi-finished product. In this case, the semi-finishedproduct formed by rolling and/or casting serves as a base for thefinished product formed by forging. This ensures that there is less lossof material during the forging and simplifies the forging process.

In one possible embodiment, the semi-finished product comprises aprojecting part. This projecting part is suitable for holding thesemi-finished product and orienting it during forging. After the forgingprocess, this part is removed. However, it is also possible for theprojecting part by which the trailing arm is held not to be removedduring forging, but for it to be part of the finished trailing arm. Allthis depends on the design of the trailing arm. An advantage thereof isthe fact that even less material is required to manufacture the trailingarm.

After forging, the trailing arm is preferably hardened by means of ahardening process. This hardening process is preferably performed on thesurface of the trailing arm.

A seventh aspect of the invention relates to a method for producing atrailing arm for a wheel axle suspension, preferably a pneumaticallysprung wheel axle suspension, wherein the trailing arm has a securingeye at the front end. As is known, the trailing arm is in practiceconnected to a bearing bracket by means of the securing eye and a pin(if desired designed as a bolt) inserted through the eye, which bearingbracket is in turn attached to the chassis of the vehicle.

It is an object of the seventh aspect of the invention to provide animproved and/or alternative manufacturing process for such a trailingarm.

The seventh aspect of the invention provides a method, whereinmethod—following the formation of the securing eye—the trailing arm istwisted about the longitudinal axis of the trailing arm, so that thesecuring eye is rotated through an angle, said twisting preferablytaking place in a portion of the trailing arm which adjoins the securingeye.

The seventh aspect of the invention can advantageously be used forproducing spring trailing arms of suitable steel.

An advantage of this method is the fact that the orientation of thesecuring eye can be adapted to the desired position in the wheel axlesuspension.

A wheel axle is sometimes produced in the form of a bend in order tomake space, for example, for a cardan shaft. In most cases, a trailingarm is then attached to a horizontal part of the wheel axlecorresponding to a horizontally oriented hinge pin of the securing eye.By twisting the trailing arm and orienting the securing eye in thismanner, the trailing arm can be attached to any part of the wheel axle,it being possible for the hinge pin to remain oriented horizontally inthe fitted position (as is usual), while allowing the trailing arm to beattached to an oblique part of the wheel axle. In this case, anyrotation can be used, preferably 1° to 90°, but larger rotations, suchas for example 120°, are also possible.

A second advantage offered by this method relates to the manufacturingprocess. The invention makes it possible for the securing eye to beoriented differently during a step of the manufacturing process than inthe finished wheel axle suspension. By now carrying out themanufacturing process with the eye at a different orientation andsubsequently twisting the trailing arm, preferably in a defined region,which preferably has a round cross section, in order to reach the finalorientation of the securing eye, the manufacturing process can beoptimized.

Preferably, the trailing arm is, at least partially, produced byforging.

In one embodiment, the trailing arm is formed from a semi-finishedproduct, the width being greater than the thickness of the semi-finishedproduct. The securing eye is then, possibly in one blow, formed using aforging hammer in a pre-forming position of the eye, with the axis ofthe hole in the eye at that point in time still being in the thicknessdirection, that is to say at right angles to the width of the trailingarm, in particular when the spring trailing arm has a spring portionwhich has a substantially rectangular cross section. The forging hammerpreferably also moves in said thickness direction, i.e. in fact at rightangles to the principal plane of the trailing arm. The securing eye isthen moved to the desired position by twisting a part of the trailingarm. The desired position of the eye will usually be rotated through 90°with respect to the pre-forming position, with the axis of the hole inthe eye, after twisting, running substantially parallel to the width ofthe trailing arm.

When forming the securing eye, the forging hammer is possibly designedas the complementary portion of the half of the securing eye to beformed. On the other side of the forging hammer, an anvil is providedwhich is complementary with the other half of the securing eye to beformed. By now placing the portion to be formed between the forginghammer and the anvil, the securing eye can be formed, preferably withone blow.

Forming the trailing arm with the securing eye by forging offers theadvantage that the forming process is quick compared to, for example, aprior art process using rollers wherein the eye has to be formed laterby means of bending. This is advantageous for the time of passage of thetrailing arm to be produced. In addition, forging makes it possible toproduce an eye having a closed annular body portion surrounding the holeof the eye. This results in a strong eye and, compared to bending arolled portion of the trailing arm, as is used in the prior art withspring trailing arms, has the advantage that there is no interruption inthe material at a seam and no welding operation is required in order toclose this seam.

It is conceivable that several blows of the forging hammer are requiredin order to form the securing eye. This is the case, for example, whenthe shape of the securing eye is relatively complicated.

Preferably, the securing eye formed by forging does not require anyshape-defining finishing, but with more complicated shapes and/or morestringent requirements with regard to tolerances, it is expected thatone or more, preferably simple finishing operations may be required toproduce the final shape of the securing eye.

In one advantageous embodiment, a portion having a substantially roundcross section, in particular a circular cross section is formed,adjacent to the securing eye, in such a manner that during twisting ofthe arm, the deformation takes place completely or at leastsubstantially within the portion having the substantially round crosssection.

Preferably, the trailing arm, or at least the front end thereof with thesecuring eye and the portion having a round cross section which isprovided, if desired, and adjoins the securing eye, is formed in itsentirety by forging in a forging device. In this case, the eye ispreferably formed from a portion of the trailing arm which wasoriginally—prior to forging—circular, with the hole being formed in theeye by forging. If desired, a hole could already be present in theoriginally circular portion.

Preferably, twisting takes place after forging using a twisting device,when at least the portion of the trailing arm which is to be twisted ishot, in practice red-hot, preferably still hot from forging and/or as aresult of suitable heating of the part to be twisted. Preferably,twisting takes place in a single uninterrupted twisting movement untilthe desired position of the securing eye has been reached.

An eighth aspect of the invention relates to a wheel axle suspensionhaving, among other things, a trailing arm having a portion which has asubstantially round cross section (114), in particular a circular crosssection. In this case, there is provided a trailing arm for a wheel axlesuspension for suspending an axle body of a wheel axle from a vehicle,which trailing arm has a securing eye at a front end for attaching thetrailing arm to the vehicle, for example to a bearing bracket which isprovided on the vehicle chassis, for example using a hinge bolt.Adjacent to the securing eye, the trailing arm has a portion which has asubstantially round cross section, in particular a circular crosssection.

One advantage of this round cross section is the fact that stresses inthe material resulting from torsion due to, for example, a rollingmotion of the vehicle, are distributed virtually evenly along theperiphery of the cross section, where the deformation and the stress isgreatest.

Another advantage of this aspect of the invention becomes clear incombination with the twisting of the trailing arm in order to orient thesecuring eye. When the portion of the trailing arm which is adjacent tothe securing eye has a substantially round cross section before thesecuring eye is twisted and the deformation during twisting takes placecompletely or substantially in the portion having the substantiallyround cross section, this not only results in uniform stresses along theperiphery of the cross section, but the shape of the portion of thetrailing arm which is adjacent to the securing eye is also substantiallyidentical to the situation prior to twisting and there is lesssuperfluous material.

In one embodiment, the trailing arm comprises at least one portionhaving a substantially rectangular cross section between the securingeye and the arm region where the axle body is connected to the trailingarm. This has the advantage that the stiffness of the trailing arm canbe optimized in various directions. This is particularly advantageous ifthe trailing arm also has to absorb transverse forces, for example whenthe vehicle goes around a bend.

In order to prevent peak stresses or stress concentrations as much aspossible, the portion having the substantially round cross section thenpreferably merges smoothly with the portion having the substantiallyrectangular cross section.

The eighth aspect of the invention can be used with both sprung andrigid trailing arms. If the trailing arm is a spring trailing arm andhas a portion which has a substantially rectangular cross section, thisportion is preferably the spring portion.

In one embodiment, the trailing arm, or at least the front part thereof,is produced by means of forging, preferably according to one or moreaspects of the invention.

It will be clear to those skilled in the art that the forged trailingarms according to the various aspects and preferred embodiments of theinvention, as is already customary for pneumatically sprung wheel axlesuspensions for lorries, trailers and the like, are preferably designedas monolithic and solid parts made from a suitable steel grade,particularly spring steel in the case of spring trailing arms.

It will be clear to those skilled in the art that the various aspects ofthe invention can be used separately, but also in all kinds of differentcombinations. Non-limiting examples of the aspects and of combinationsof these aspects of the invention will be explained below with referenceto the drawing.

The invention also relates to a vehicle provided with a wheel axlesuspension according to one or more aspects of the invention and/or atrailing arm according to one or more aspects of the invention, thewheel axle suspension preferably being pneumatically sprung. The vehicleis for example a lorry or a lorry trailer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a perspective view at an angle from above of a preferredembodiment of a trailing arm for a wheel axle suspension according tothe invention;

FIG. 2 shows a perspective view at an angle from below of the trailingarm from FIG. 1;

FIG. 3 shows a side view of an axle clamping arrangement wherein a roundaxle is clamped against the trailing arm from FIG. 1;

FIG. 4 shows a side view of a wheel axle suspension according to theinvention with an alternative embodiment of a trailing arm;

FIG. 5 shows a perspective view of another alternative embodiment of atrailing arm for a wheel axle suspension according to the invention;

FIG. 6 shows a side view of a shell part which can be used with thetrailing arm from FIG. 5;

FIG. 7 shows a side view of a trailing arm for an alternative wheel axlesuspension according to the invention;

FIG. 8 shows a side view of yet another alternative wheel axlesuspension according to the invention;

FIG. 9 shows a top and side view of an alternative exemplary embodimentof a trailing arm for a wheel axle suspension according to theinvention;

FIG. 10 shows a side view of a bearing bracket and vehicle chassis withan absorber securing part according to the invention fitted thereto; and

FIG. 11 shows a highly diagrammatic view of a trailing arm with asecuring eye according to the invention in a pre-forming position and adesired position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 and FIG. 2 show a spring trailing arm 1, which is also referredto in the art as a flexible trailing arm. The trailing arm 1 has aspring portion 2 which is provided at the front, viewed in the directionof travel of the vehicle, with a securing eye 3. The trailing arm 1 can,by means of a hinge bolt, be hingedly connected to a bearing bracketwhich is provided on the underside of a vehicle chassis. The bearingbracket or equivalent supporting structure can also be integral with thevehicle chassis.

Following on from the spring portion 2 of the trailing arm 1, a curvedportion 4 is formed, which curved portion 4 has a concave contactsurface 5 which is directed downward in the example shown. Following onfrom the curved portion 4, an end portion 6 is formed which is intendedfor fitting a pneumatic spring thereto. The illustrated trailing arm 1has a shape which is referred to in the field as “gooseneck”.

The spring portion 2 of this arm 1 has a substantially rectangular crosssection having a width and a thickness, the width being greater than thethickness. The spring portion 2 may be produced by rolling, but couldalso be produced by forging. The curved portion 4 is preferably producedby forging.

In this case, four bore holes 7 are provided in the curved portion 4which serve to insert clamping bolts. The bore holes 7 are recessed withrespect to the top surface of the curved portion.

FIG. 3 shows how an axle body 10 which is designed as a relativelythin-walled, substantially round tube is clamped against the trailingarm 1. Such a tubular axle body has, for example, an outer diameter of146 mm and a wall thickness which is between 7 and 9 mm. Such an axlebody can be deformed in the radial direction relatively easily.

FIG. 3 shows that the axle clamping arrangement here comprises a supportpart 20, as is preferred in combination with a hollow axle body. Thesupport part 20 has a recess 21 in which a part of the axle body 10 isaccommodated. In the fitted position, a part of the periphery of theaxle body 10 is clamped against the inner wall 22 of the recess 21,which inner wall 22 is complementary with the outer contour of the axlebody 10. The support part 20 is clamped against the underside of theaxle body 10 by means of bolts 23, having a bolt head 23 a and a boltshank 23 b, which are inserted into bore holes 7 in the trailing arm 1,and by means of nuts 24.

As can clearly be seen in FIG. 3, more than 180° of the periphery of theaxle body 10 bears against the inner wall 22 of the support part 20. Theinner wall 22 of the support part 20 and the contact surface 5 of thecurved portion 4 of the trailing arm 1 surround virtually the entireperiphery of the axle body 10, as FIG. 3 clearly illustrates. This isadvantageous when clamping relatively thin-walled axles since the loadis omnidirectional, as a result of which the axle body 10 remains roundat the location of the clamping arrangement.

In this example, the curved portion 4 of the trailing arm 1 is widerthan the spring portion 2. The width of the spring portion 2 is suchthat the rolling motion of the vehicle can be withstood. The curvedportion 4 is wider, resulting in a lower surface pressure on the axlebody, in particular when absorbing transverse forces. The round hollowaxles can be clamped directly against the trailing arm, without the useof an axle pad or another fitting piece. It is known from the prior artto arrange an axle pad between the axle and the trailing arm, which axlepad is arranged in a fitting manner against the axle body on that sidewhich is turned towards the axle and is arranged in a fitting manneragainst the trailing arm on that side which is turned towards thetrailing arm.

In the context of the first aspect of the invention, however, provisionis made for a so-called galvanized plate to be fitted between the axlebody and the trailing arm. This relatively thin galvanized plate offerscathodic protection against stress corrosion of the trailing arm, butdoes not serve any purpose in connection with arranging the axle bodyand the trailing arm together in a fitting manner.

FIG. 3 shows a possible embodiment of the front clamping bolts 23. Thebolt heads 23 a of the front clamping bolts 23 are provided withsecuring lips 25 to which a shock absorber 26 is hingedly attached. Thesecuring lips 25 extend from the bolt head 23 a upwards and to the frontat an angle. It is also possible for a single bolt head to be providedwith several lips or with a fork, for example in order to arrange theeye of a shock absorber therebetween.

The axle body 10 is preferably locked against rotation with respect tothe trailing arm 1. In theory, there are several options for lockingPreferably, locking is effected by providing a recess or depression inthe contact surface 5 and to provide a projection on the axle body 10,for example in the form of a welded-on spline 11, as is illustrated inNL1022395. In addition to locking against a movement of the axle withrespect to the trailing arm resulting from the action of torsionalforces, for example due to the wheels of the vehicle braking, theprojection and the recess furthermore also form a positioning means foraxially correctly positioning the axle in the correct manner duringassembly. Another possibility of locking against rotation is to providea projection, for example in the form of a segment of a sphere, on thecontact surface 5. The axle may be provided with a recess or depressionas is illustrated in EP 1 334 848 in the name of Schmitz Cargobull AG.

In addition to the possibility of locking the axle body 10 with respectto the trailing arm, an embodiment is also conceivable wherein the axlebody 10 is locked in a similar way with respect to the support part 20.A variant involving locking of the axle body 10 with respect to both thetrailing arm and the support part is also possible. The same applies tothe embodiments which have been illustrated in FIGS. 4 and 5.

FIG. 4 shows a wheel axle suspension for suspending a round hollow axle10 from a vehicle. The wheel axle suspension comprises on both sides ofthe vehicle a trailing arm 41 which extends in the longitudinaldirection and to which the axle 10 is attached. The trailing arm 41 ishingedly connected at the front, viewed in the direction of travel ofthe vehicle, to a bearing bracket 42 which is arranged on the undersideof the vehicle chassis 43. At the rear, a pneumatic spring 44 is fittedbetween the trailing arm 41 and the chassis 43.

In the assembled state, the axle body 10 bears directly against acontact region 45 of the trailing arm 41. The shape of the contactregion 41 is essentially complementary to the outer contour of the axlebody 10. On the side of the axle body 10 which is turned away from thecontact region 45 of the trailing arm 41, a support part 46 is presentwhich is provided with a recess for accommodating the axle 10. Thetrailing arm and the support part 46 are clamped against the axle body10 by means of clamping bolts 47 and nuts 48.

In this example, the front clamping bolts 47 are provided on their boltheads with a securing lip 49 to which an end of a shock absorber 401 isattached. The other end of the shock absorber 401 is connected to thebearing bracket 42 or directly to the chassis.

On the support part 46, an additional arm 461 is fitted which extends tothe front and upwards at an angle from the support part 46 and isconnected to the trailing arm 41 on the end which is turned away fromthe support part. The connection between the additional arm 461 and thetrailing arm 41 serves to reduce the load on the trailing arm 41. Theadditional arm 461 can be designed as a spring.

FIG. 5 shows an alternative embodiment of a trailing arm. On the frontend which is to be fitted to the bearing bracket, the trailing arm 51has a securing eye 53, by means of which the trailing arm 51 can beattached to the bearing bracket by means of a hinge bolt. The trailingarm 51 has a spring portion 52. Adjacent to the spring portion 52 of thetrailing arm 51, a curved portion 54 is formed, which curved portion 54has a concave contact surface 55 which is facing upwards in theillustrated example. The curved portion 54 tapers towards the springportion in the width direction.

FIG. 5 furthermore shows a support part 56 which is positioned oppositethe curved portion and has a recess 57 for accommodating a part of theperiphery of the axle body.

For the sake of clarity of the drawing, the axle body has been omittedin this FIG. 5. In the fitted position, a part of the periphery of theaxle body bears against the inner wall 58 of the recess 57, which innerwall 58 is complementary to the outer contour of the axle body. Thesupport part 56 is clamped against the top side of the axle body bymeans of bolts (not illustrated). To this end, the support part isprovided with securing holes 561.

As can clearly be seen in FIG. 5, more than 180° of the periphery of theaxle body lies against the inner wall 58 of the support part 56.

In this example, the inner wall 58 of the support part 56 and thecontact surface 55 of the curved portion 54 of the trailing arm 51surround virtually the entire periphery of the axle body 10, as FIG. 5clearly shows. This is advantageous when clamping relatively thin-walledaxles since the load is then omnidirectional, as a result of which theaxle body 10 remains round at the location of the clamp. Incidentally,it is also conceivable for the curved portion of the trailing arm tosurround the periphery of the axle body over more than 180°.

The support part 56 is provided with a securing arm 59, which in thiscase is integrally formed with the support part, which arm 59, in thefitted position, extends from the support part 56 to the rear. Thesecuring arm 59 is designed so that the underside of a pneumatic spring(not shown) can be fitted thereto. The top side of the pneumatic springis attached to the vehicle chassis. Thus, the pneumatic spring in thiscase acts on the hingedly connected trailing arm 51 via the support part56.

In this example, the support part 56 is provided with two securing lips562 at the top side which extend upwards and to the front at an angle.In the fitted position, a securing eye of a shock absorber is arrangedbetween the securing lips 562, which securing eye is hingedly connectedto the securing lips 562 by means of a bolt.

It is also possible to omit the securing lips 562 and instead use, forexample, the bolts 23 shown in FIG. 3 and having a bolt head 23 a whichis provided with a securing lip 25.

In practice, axle bodies with different outer diameters are used. Thus,trailers often use an axle body with an outer diameter of 146 mm, whilelorries for example use an axle tube of 127 mm. As has been describedabove, according to one aspect of the invention, the curved portion 54with the concave contact surface 55 of the trailing arm 51 may bedesigned to bear directly against an axle body having a specificdiameter, for example 146 mm or 127 mm.

According to one aspect of the invention, the trailing arm 51 isproduced for a large outer diameter of the axle body, for example 146mm, and can then also be used for axle bodies having a smaller diameter,for example 127 mm. According to one aspect of the invention, thisbecomes possible by arranging a shell part 60 (see FIG. 6) between thecurved portion and the axle body, which shell part 60 has an innercontact surface 61 having an inner diameter which corresponds to theouter diameter of the axle body, and has an outer contact surface 62having an outer diameter which can be arranged in a fitting manneragainst the contact surface 55 of the curved portion 54 of the trailingarm 51.

The shell part 60 is preferably produced by casting. According to thisaspect of the invention, it is also possible for the support part 56 tobe provided with a recess 57 which is adapted to the outer diameter ofthe axle body.

In one possible embodiment, the contact surface 55 of the curved portion54 of the trailing arm 51 is adapted to an axle tube having an outerdiameter of 146 mm. In the curved portion 54, the outer contact surface61 of a shell part 60 is arranged against the contact surface 55 of thecurved portion 54 of the trailing arm 51, which shell part 60 has aninner contact surface 61 having an inner diameter of 127 mm. Theassociated support part 56 has a recess 57 with an inner diameter of 127mm.

In addition to the recess 57, it is also possible for the shape andlength of the arm 59 of the support part 56 to be adapted to thespecific variant of the wheel axle suspension. In this manner, auniversal trailing arm 51 can be produced which is suitable for variousvariant embodiments of wheel axle suspensions, whereas one specificsupport part 56 is produced for each variant embodiment. This makes itpossible to produce the trailing arm 51 in large numbers which reducesthe production costs per trailing arm as the production line only has tobe designed to manufacture one single trailing arm 51. This isparticularly advantageous if the trailing arm 51 is produced by means ofrelatively expensive processing steps, such as rolling and/or forging,which will, according to the invention, often be the case when producingflexible trailing arms.

The support part 56 is preferably produced in several variants,depending on the variant embodiments, in particular diameters, of thespecific wheel axle suspensions.

Preferably, the support part 56 with the integrally formed arm 59 isproduced by forging or casting, in which case it should be pointed outthat casting is less expensive than forging in the case of relativelysmall production numbers.

With the embodiment from FIG. 5, a locking against rotation ispreferably provided between the support part 56 and the axle body, inparticular when a shell part 60 is used.

FIG. 7 shows a part of another embodiment of a wheel axle suspensionaccording to the invention. The wheel axle suspension comprises atrailing arm 71 which is similar to the trailing arm 51 which is shownin FIG. 5. At the end which is to be fitted to the front, the trailingarm 71 has a securing eye 73 with which the trailing arm 71 can beattached to a bearing bracket by means of a hinge bolt. The trailing arm71 has a spring portion 72. Adjacent to the spring portion 72 of thetrailing arm 71, a curved portion 74 is formed, which curved portion 74has an upwardly directed concave contact surface 75. The curved portion74 here has a greater width than the spring portion 72.

FIG. 7 furthermore shows a support part 76 which is positioned oppositethe curved portion and has a recess 77 for accommodating a part of theperiphery of the axle body 10. In the fitted position, a part of theperiphery of the axle body 10 is clamped against the inner wall 78 ofthe recess 77, which inner wall 78 is complementary to the outer contourof the axle body.

In this example, the support part 76 is clamped against the top side ofthe axle body 10 by means of U-shaped clamping straps 80. In thisexample, the top side of the support part 76 is provided with recesses79 which extend essentially in the transverse direction and at leastpartially accommodate the bend of the U shape. The downwardly extendinglegs of the clamping straps 80 are situated along the sides of thesupport part 76. Using clamping straps 80 instead of bolts (cf. FIGS. 5and 7) has the advantage that the stretch length increases and the lossof prestress is prevented more effectively.

A separate absorber securing part 90 is clamped at the front of the axlebody 10, between the front end of the support part 76, that is to saywhere the front clamping strap 80 surrounds the support part 76, and thetrailing arm 71, at the location of the transition between the springportion 72 thereof and the curved portion 74 thereof.

In this example, the absorber securing part 90 has a rear concavesurface 91 which, in the fitted position, bears against the axle body10. In this example, the absorber securing part 90 has a fewthrough-holes through which the legs of the front U-shaped clampingstrap 79 extend. When the nuts 81 on the legs of the clamping straps 80are tightened, the absorber securing part 90 is clamped securely.

As can be seen in FIG. 7, approximately 180° of the periphery of theaxle body 10 bears against the inner wall 78 of the support part 76. Theinner wall 78 of the support part 76, that part of the absorber securingpart 90 which is turned towards the axle body 10, and the contactsurface 75 of the curved portion 74 of the trailing arm 71 surroundvirtually the entire periphery of the axle body 10, as FIG. 7 clearlyshows. This is advantageous when clamping relatively thin-walled axles,since the load is then omnidirectional, as a result of which the axlebody 10 remains round at the location of the clamping arrangement.

In this example, the front of the absorber securing part 90 is providedwith two securing lips 82 which extend upwards and to the front at anangle. Each securing lip 82 is provided with a bore hole 83 throughwhich a bolt (not shown) extends in the fitted position. In the fittedposition, a securing eye of a shock absorber is situated between thesecuring lips 82, which securing eye is hingedly connected to thesecuring lips 82 by means of said bolt.

Similar to the support part 56, the support part 76 is provided with asecuring arm 769, which extends from the support part 76 to the rear inthe fitted position. The securing arm 769 is designed so that theunderside of a pneumatic spring (not shown) can be fitted thereto. Thetop side of the pneumatic spring is attached to the vehicle chassis.Thus, the pneumatic spring in this case acts on the hingedly connectedtrailing arm 71 via the support part 76.

The embodiment from FIG. 7 also offers the possibility of using a shellpart 60, as has been described above with reference to FIGS. 5 and 6.

FIG. 8 shows a variant of the wheel axle suspension from FIG. 5. Thewheel axle suspension comprises a trailing arm 51 which substantiallycorresponds to the trailing arm 51 which is shown in FIG. 5 and hasalready been described above. The support part 56 is connected to thecurved portion 54 by means of bolts. An extension bush 91 is in eachcase placed on the support part 56, above the front securing holes 561.The front bolts 92 extend through this extension bush 91 and, in thefitted position, the bolt head 92 a is on the end side on the top sideof the extension bush 91. Preferably, that side of the extension bush 91which is turned to the front (viewed in the direction of travel of thevehicle) is provided with a securing lip 93 having a bore hole 94. Inthe fitted position, a hinge bolt is inserted into bore hole 94 in orderto hingedly attach an eye of a shock absorber to the lips 93. The use ofan extension bush 91 means that bolts 92 having a longer bolt lengthhave to be used, which offers the advantage that the stretch lengthincreases and the loss of prestress is prevented more effectively. Anextension bush could also be used with the rear clamping bolts, whichwould mean that longer bolts would have to be used there as well and thestretch length increases. An extension bush 91 can, if desired, also bedesigned without an absorber securing lip 93 in order to achieve thatadvantage, which is regarded as a further aspect of the invention.

FIG. 9 shows two views of a trailing arm 110 according to the invention.FIG. 9A shows a top view of a spring trailing arm 110 comprising asecuring eye 111, a curved portion which forms the contact region 112which can accommodate the axle clamp, and a spring portion 113 betweenthese two parts. In the fitted position, the securing eye 111 isattached to a bearing bracket (not shown). The securing eye 111 is atthe front of the trailing arm 110 and the portion which forms thecontact region 112 is situated, in this example, at the rear of thetrailing arm 110.

Holes are provided on both sides of the contact region 112. Two holes120, 121 at the front of the contact region 112, and one hole 122 at therear of the contact region 112. Clamping bolts or the shanks of U-shapedclamping straps are inserted through these holes 120-122 in order toclamp the trailing arm 110 to an axle body (not shown). Other clampingmeans are also possible.

This example clearly shows that the trailing arm 110, at the location ofthe contact region 112, is wider at the front of the contact region 112than in the region which is situated in front thereof (in the directionof the securing eye 111) and the rear of the contact region 112 of thetrailing arm 110. This measure creates a large contact surface in thearea where the load is highest, i.e. at the front of the contact region,using a minimal amount of material, so that the axle body is notundesirably deformed as a result of being clamped.

In this example, depressions 125, 126 have also been provided on theoutside of that portion of the trailing arm which forms the contactregion 112, with depression 125 extending from hole 120 in the directionof hole 122, and depression 126 extending from hole 121 in the directionof hole 122.

As can be seen, that portion of the trailing arm which forms the axleclamping has, on that side which is turned away from the axle body, acentral rib 124 which extends from the front of the contact region,between the two holes 120, 121 on said front, in the direction of thesingle hole 122 at the rear of the contact region. On either side ofthis central rib 124, there are depressions 125, 126, wherein in eachcase one of the holes at the front is provided.

As is preferred, a further rib 124 a, 124 b is provided along each sideedge of the respective portion and delimits the depression on that side.

The embodiment which has been illustrated and described above provides asaving on material while the portion which forms the contact region 112is sufficiently strong.

In this exemplary embodiment, flat surface portions 127-129 are providedround the holes 120-122. This make it possible for a bolt head or nut tobear against the trailing arm 110 in a neat manner and to transfer theclamping forces onto the trailing arm 110 in an effective manner atrelatively low peak stresses. In one variant, it is possible to selectthe dimensions of the holes and associated clamping means (clampingbolts or straps) in such a manner that clamping of the axle body leadsto uniform stresses in the clamping means.

FIG. 9B shows the spring trailing arm 110 from FIG. 9A in side view. Thetwo views, FIG. 9A and FIG. 9B together, clearly show that the trailingarm has a portion 114 which is adjacent to the eye 111 and has asubstantially round cross section. If the trailing arm 110 is nowsubjected to a torsional load, this results in virtually uniformdeformations and stresses along the periphery of the portion 114.

It is also possible to twist the arm 110 in the region 114 duringproduction of the trailing arm in order to adjust the position of theeye 111 to that required for fitting the trailing arm in the wheel axlesuspension. No significant change in shape of the portion 114 can beobserved during this twisting operation.

It is possible for the securing eye 111 to be formed in a differentposition during a manufacturing process, such as forging, after which itis, for example, turned by a quarter turn to a desired position and thusassumes the position illustrated in FIGS. 9A and 9B. In this context,see also FIGS. 11A and 11B. The advantage thereof is that this makes iteasier to form the securing eye 111 during the manufacturing process, inother words fewer forming steps or less complicated forming steps arerequired, following which the arm 110 only has to be twisted locally.

It is possible to produce the trailing arm 110 in a single operation byforging. Preferably, the eye is also forged and this may renderfinishing of the hole of the eye 111 superfluous.

Preferably, the eye 111 is forged in such a manner that after forgingthe eye has a closed annular body portion surrounding the hole of theeye, resulting in an eye of great strength.

It should be noted that, for example, a trailing arm 51 which isillustrated in FIG. 5 can also be formed by forging. In this case, onlythe hole in the eye 53 which is at right angles to the direction of theforging direction (from top to bottom), has to be provided by afinishing operation, for example boring.

Between portion 114 and the portion which forms the contact region 112,the spring portion 113 is present, which in this example has asubstantially rectangular cross section. As a result, the trailing arm110 has different stiffness in different directions, which isadvantageous, for example, if the trailing arm 110 is also subjected totransverse loads.

In this example, portion 114 merges smoothly with the spring portionhaving the substantially rectangular cross section. This prevents peakstresses in the material.

The shape of the trailing arm 110 is such that it can be produced in itsentirety by forging. Mainly the portion which forms the contact region112, the front portion 114 and the securing eye 111 are pre-eminentlysuitable to be formed by forging and are a good example of theadditional freedom of design for each portion of the arm compared to theprior-art spring trailing arms which are produced only by means ofrolling.

FIG. 10 shows a bearing bracket 130 which is connected by means ofbolt/nut connections to vehicle chassis 131, in this case a longitudinalmember of the chassis. In this example, the bearing bracket consists oftwo plates, each of which is connected to the longitudinal member bymeans of bolt/nut connections 132. In addition, part of an absorber 135which is known per se can be seen, which usually has a telescopic bodywith a securing eye 136 at each end. The absorber securing part 140 ismade of metal and has one or more lips or a fork 141 for attaching theeye of the absorber. Said one or more lips may be at an angle, forexample approximately in line with the axis of the absorber. Thesecuring part 140 furthermore has an integral bolt shank 142, in thisexample a single bolt shank, as is preferred. An opening has beendrilled in the vehicle chassis, in this case close to the bearingbracket, through which the bolt shank extends. A nut 143 is screwed ontothe bolt shank. The advantage is now that the forces are passed directlyto the vehicle chassis by the shock absorber, resulting in lessstringent requirements being placed on the bearing bracket and thusleading to an improved design.

FIG. 11A shows a front portion 154 of a trailing arm 150, a securing eye151 being attached to the front potion 154. The front portion 154preferably has a substantially round cross section.

Eye 151 is now in the pre-forming position, that is to say the positionin which eye 151 is formed. Forming has in this case taken place fromthe top downwards, preferably by means of a forging device.

After the eye 151 has been formed, eye 151 can still be rotated into adesired position. An example of a desired position is illustrated inFIG. 11B, in which arrow T indicates the rotation of the eye 151. Therotation of the eye 151 has been carried out by twisting the trailingarm in the adjacent front portion 154. In this example, the eye 151 isrotated a quarter turn, but other rotations between 1° and 90°, forexample 45°, are also possible. It is also possible to rotate the eye bymore than 90°, for example by 120°.

As a result of the round cross section of the front portion 154, no orhardly any change in shape can be seen after twisting. Twisting couldalso take place in a front portion having a different cross section, forexample a rectangular cross section.

It should be noted that the invention is not limited to the specificexamples illustrated in the drawing. The person skilled in the art willeasily be able to think of variations and combinations of elements fromthe different exemplary embodiments illustrated and these are deemed tofall within the scope of the invention.

1. A wheel axle suspension for suspending an axle body of a wheel axlefrom a vehicle, comprising on both sides of the vehicle a trailing armwhich extends in a longitudinal direction of the vehicle and to whichthe axle body is attached, which trailing arm is hingedly connected at afront end thereof, viewed in a direction of travel of the vehicle, to abearing bracket which is arranged on a vehicle chassis, as well as apneumatic spring which is operational between the trailing arm and thechassis; wherein the axle body, in a fitted position, bears directlyagainst a contact region of the trailing arm, which contact region isessentially complementary to an outer contour of the axle body, thetrailing arm being clamped against the axle body by means of clampingmeans; wherein the trailing arm is wider at a location of at least frontof the contact region than in a region which is situated immediately infront thereof; and wherein the trailing arm has a portion which formsthe contact region, said portion, in top view, having an approximatelytriangular shape, a greatest width of which is situated at a front endof said portion and a tip of the approximately triangular shape beingsituated at a rear end of said portion.
 2. The wheel axle suspensionaccording to claim 1, wherein a support part is provided on a side ofthe axle body which is turned away from the contact region of thetrailing arm, and is provided with a recess for accommodating the axlebody, the clamping means clamping the axle body between the support partand the contact region of the trailing arm.
 3. The wheel axle suspensionaccording to 2, wherein the support part surrounds the axle body over atleast 180° of a periphery of the axle body.
 4. The wheel axle suspensionaccording to claim 1, wherein the axle body is round and hollow in crosssection.
 5. The wheel axle suspension according to claim 1, wherein theaxle body has a substantially circular cross section at a location whereit is clamped against the trailing arm.
 6. The wheel axle suspensionaccording to claim 1, wherein the trailing arm, at a location where itis clamped against the axle body, is provided with one or more holes onboth sides of the axle body for inserting clamping bolts or shanks ofU-shaped clamping straps.
 7. The wheel axle suspension according toclaim 1, wherein the trailing arm is designed as a spring trailing arm.8. The wheel axle suspension according to claim 7, wherein the trailingarm is at least partially produced by forging.
 9. The wheel axlesuspension according to claim 1, wherein the portion of the trailing armwhich forms the contact region tapers towards a rear end.
 10. The wheelaxle suspension according to claim 1, wherein a support part is providedwith a securing arm for the pneumatic spring, and wherein the axle bodyis clamped between the trailing arm and the support part, and whereinthe securing arm extends further towards a rear and wherein the clampingmeans clamps the trailing arm and the support part against the axlebody.
 11. The wheel axle suspension according to claim 10, wherein twoholes are provided near the wide front end of the portion of thetrailing arm which forms the contact region, and a single hole isprovided at the narrower rear end of said portion.